System for measuring the characteristics of electrical apparatus



May 10, 1938. c. LEMMON 2,116,606

SYSTEM, FOR MEASURING THE CHARACTERISTICS OF ELECTRICAL APPARATUS Filed Nov. 17, 1934 4 Sheets-Sheet 1 //V l/EA/TOR c1. zwmz/ May 10, 1938. c. 1.. LEMMON 2,116,606

SYSTEM FOR MEASURING THE CHARACTERISTICS OF ELECTRICAL APPARATUS Filed Nov. 17. 1934 4 Sheets-Sheet 2 3) HQ MW A 7 TOR/Vi y 10, 1933- I c. L. LEMMON 2,116,606 SYSTEM FOR MEASURING THE CHARACTERISTICS OF ELECTRICAL AECARATUS Filed Nov. 17. 1934 4 Sheets-Sheet s awn/ran g, wmw

"CLLEMMo I Patented May 10, 1938 UNITED STATES PATENT OFFICE SYSTEM- FOR MEASURING THE CHARAC- TERISTIQS OF ELECTRICAL APPARATUS Clair L. Lemmon, Mount Airy, M1, assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application November 17, 1934, Serial No. 753,507

18Claims.

This invention relates to systems for measuring the characteristics of electrical apparatus, and more particularly to an, automatic capacitance measuring and recording system.

It is an object of the present invention to pro- 4 v vide a system for automatically measuring and recording characteristics of electrical apparatus.

In accordance with one embodiment of the invention there is provided apparatus for 'auto-" matically measuring and recording the capacity unbalance between two'pairs of conductors in a telephone cable; the capacity unbalance between a phantom circuit, embodying the four wires of the two pairs of wires, and each pair of wires, and

the capacitance to ground from each wire of the formed by the wires of a telephone cable;

Fig. 4 is a circuit diagram which shows schematically the circuit as connected to measure the capacitance between the two pairs of conductors in the cable, and

Fig. 5 is a circuit diagram which shows sche-' Tfi'atically the'circuit as connected to measure the capacitance between the phantom circuit andone of the pairs of wires.

In the embodiment of the invention disclosed herein the two pairs of wires of the telephone cable between which it is desired to measure the capacitance are connected to an alternating current capacitance bridge circuit including a motor driven air condenser having associated therewith a commutator which rotates with the movable plates 'of the motor driven air condenser. The capacitance between the two pairs ofconductors is measured within the limits of the capacity of driven condenser, additional fixed condensers are automatically included in the circuit until a condition of balance is arrived at by the bridge, whereupon the bridge which has a thermionic valve connected thereto through a transformer, will operate the valve and cause it to trip a second valve which in turn will complete circuits to those of a plurality of valves having the grids thereof 55 connected to brushes engaging the commutator totrlp these valves which in turn control through a series of relays a solenoid controlled typewriter. After the capacitance unbalance between the pairs 01' wires has been measured, the bridge will automatically be started through a control system comprising groups of relays and selector switches to connectthe four wires of the two pairsof wires to the bridge in a diiferent manner to measure the capacitance between one pair of wires and the phantom circuit which will eventually include all four wires of the two pairs of wires. This measurement is made and recorded in substantially the same manner as the measurement between the two pairs of wires whereupon the control system will automatically test the capacitance between the other pair of wires and the phantom circuit. The measurements; so determined will then be recorded, and a sounder will be operated to indicate that the test of the v four wires is completed.

Referring to the drawings in which similar parts are'designated by the same numerals in the several views, it is believed that a.clear understanding oi the invention will be had therefrom when con si'dered in conjunction with the following de-' scription.

All of the electro-mechanical parts of the system have been shown in their normal inoperative positions to simplify the disclosure; however, it

will be understood that the various parts, in the operation of the system, will assume different positions from those shown on the drawings, and these positions will be pointed out in connection with the detailed description of the device.

Referring now to the circuit diagram as disclosed in Figs. 1, 2 and 3, particular reference being had to Fig. 3, there are shown four connecting clips II, l2, l3' and H to which may be connected the four wires forming a quad" in a telephone cable. A "quad in a telephone cable is a group of four wires which are arranged, as is well known in telephone practice, to carry three talking circuits comprising two side circuits and one. phantom circuit. The method of connecting a "quad" of wires in a telephone circuit to provide three circuits for carrying telephonic conversations is well known and will not be described in detail herein, it being deemed sumcient to state that one talking circuit utilizes two wires and comprises one of the side circuits, the other side circuit utilizes the other two wires and constitutes the second circuit, and all four wires are connected to form the third or phantom talking circuit. In the specific embodiment of the invention chosen as an example the system is being used II and I2 and the other pair is secured to the L clips I3 and H. For the sake of convenience the pair of wires secured to the clips II and I2 will be hereinafter termed "side 2" and the pair .of wires secured to the clips I2 and It will be termed side I". In the use of the system, the cable may be positioned remotely from the apparatus making up the testing system and connected thereto by conductors connected to the clips II,-

I2, l3 and I4, and the control for the entire circuit may be located a scent the cable so that the operator who secure the "quad" to the clips may, upon seeming them, start the system in operation to measure the cross-talk in the quad.

The clipsIl, I2, I3 and I4 are connected to contacts of a two-way switch indicated-generally by the numeral I5 and comprising a pair of electromagnets I 5 and I1 having a common armature I8 pivoted at I! and having fixed thereto a shaft 20 on which are mounted four contact arms 2|, 22, 23 and 24. Each of the contact arms 2|. 22, 23 and 2| has associated therewith a middle contact 25, a right hand contact 26 and a left hand contact 21 and is adapted upon energizetion of the electromagnet I6 to interconnect its middle contact 25 and right hand contact 28, and upon energization of the electromagnet H -to interconnect its middle contact 25 and its left hand contact 21. The two-way switch I! is controlled by-a selector switch "having brushes I9,

' 40 and H, associated with contact blanks 42, N

and 45, respectively. The selector switch 28 is the well known selector switch used in automatic telephone systems, and is adapted upon energize.- tion anddeenergization of its electromagnet 41 to step the brushes 32, 40 and II from one on tact on their associated banks to the next contact. In addition to the selector switch 28 there are provided similar selector switches 49 and 50 operated under control of electromagnets SI and 52, respectively. The switch 42 controls the operation of four brushes N, I! and 56 and the selector switch 50 controls the operation of six brushes 51, 52, 58, 80, I and 02. These selector switches have been provided for the purpose of controlling the operation of the two-way switch I5 and two-way switches I3, I4 and I! and various relays throughout the system. The switch I2 is provided with a pair of electromagnets I1 and 18, the switch ll is provided with electromagnets I9 and 80, and the switch II is provided with electromagnets I and 82 in exactly the same manner as the eiectromagnets II and II, but are controlled through different selector switches than the electromagnets I! and I1.

' The means for connecting a cable quad to the system having been described briefly, it is believed that a clear understanding'of the invention may be had from the following description of the operation of the system in measuring the capacitance unbalance of a cable quad" which is assumed to have a side to side unbalance of +26 mmf., a phantom to side one unbalance of +102 'mmf. and a phantom to side two unbalance of 256 mmf. I The system is so arranged at the start of any testing operation, that the selector switch 38 has its brushes 39, I0 and H on either the 3rd, 6th,

anaeoe 9th, 12th, 15th, 18th or 21st contacts of their associated banks of contacts l3, l4 and 45, and the selector switches 48 and 50 have their brushes on the 1st contacts of their associated banks of contacts. At the start of a testing operation the selector switch 38 will be assumed to have its brushes 8!, 40 and 4| on the third contacts of their associated banks of contacts 42, 44 and 45 and that selector switches 49 and 50 have their brushes in engagement .with their first contacts.

With the switch 38 in the third position, the electromagnet II will be operated in a circuit from grounded battery H0 through brush 40, 3rd contact of bank 44 and winding of electromagnetll to ground and the electromagnet II will be operat'ed in a circuit from grounded battery at H0 through brush 4i and winding of the electromagnet W to ground. With the switch 50 in the 1st position, the electromagnet Si is operated in a circuit from grounded battery I25 through brush Bl, 1st contact of 'bank 6i, winding of electromagnet 2i to ground. The operation of the two electromagnets TI and II will arrange the system to make a measurement of the capacity unbalance between the two sides of the quad and the clips II, I2, I8 and I I having the wires of the quad connected thereto will be connected to a capacitance unbalance bridge I in the manner shown in Fig. 4.

The bridge I32 includes a motor driven air condenser I3I having a movable plate I32 and fixed plates I33 and I95. The fixed plate I22 is conpacity of 60 mmf. and is constantly driven at a predetermined speed through its cycle so that it will change the capacity unbalance of the bridge I20 from minus 58 mi. through zero to plus 58 mmf. by starting with 58 mmf. in arm I35 and subtracting capacity from that arm and adding it in the arm I38.

Connected to and driven with the motor driven air condenser III is a commutator II'I (Fig. 2) having a plurality of units contacts I and a plurality of tens contacts I thereon, which are all connected through a common brush I", resistances Ill and I42 to the filaments of a pair of thermionic valves I and Iii. There are associated with the units contacts III brushes I which are connected individually to the grids of five gas filled thermionic valves I and there are provided six brushes I associated with the tens contacts I for successively interconnecting the tens contacts to the grids of associated gas filled thermionic valves I". The commutator III has thereon six contacts I29 representing the values 0, 1, 2, 3, 4 and 5 in the tens denomination for controlling the recording of a tens denomination has associated therewith a set of flve units contacts representing the units value, 0, 2, 4, 6, and 8. When the bridge reaches a condition of balance, circuits will be established through the brushes I and I which at that time are in contact with their associated contacts on the commutator.

Assuming that the system is properly set up,

' also connect grounded battery at I02 through that is, the filaments of all of the thermionic valves are lighted, a sheet of paper in a typewriter I20 shown schematically in Fig. 3, and the motor driven condenser rotating, a quad may be secured to'the clips II, I2, I9 and I4 and a start key 9| operated. A preferred type of typewriter is that known commercially as the "Remington Vertical Adder the numerical keys of which are in the present embodiment of the invention operated by solenoids I2I. Momentary operation of the start key 9| will connect grounded battery at 92 through the winding of relay 99 to ground 94 causing relay 93 to operate momentarily and will connect grounded battery through one of the windings of a double wound relay 95 to ground at 95. Relay 95 upon energization will lock up in a circuit from grounded battery at 91 through the winding of the .relay and through the winding of a sounder 98 to ground at 99. The battery at 91 is a 12 volt battery and the voltage thereof is not sufiicient to operate the sounder 98. However, the ground for holding the relay 95 operated will be maintained through the sounder without op erating it. Relay 99, upon operation, and release of the key 9|, will operate momentarily and then release.

e The relay 95, in operating connects a 900 cycle alternating current from supply leads at I to the input winding of a shielded transformer IOI to supply power through the transformer IN to the bridge I90 in the manner shown in Fig. 4,

the output leads of the transformer IOI being connected through the switches I and I9 to the bridge and to the cable clips (Fig. 3). 99 in operating momentarily connects grounded battery at I02 through its make contact to one of the windings of a double wound relay I09 which will operate and lockup in a circuit from grounded battery at I05 through brush 59. in position 1 make contact of relay I09 to ground at I04. I

The momentary energization of relay 99 will the make contact of relay 99 to contacts 2 to 22 of the arcuate bank of contacts associated with brush 5i; however, since brush BI is at the start of a test on contact 1 of its associated bank the lock the relay I05 operated when operated over another circuit.

As stated hereinbefore, at the beginning of the test the selector switch 99 is in its'3rd position; that is, its associated brushes are engaging the 3rd contacts in their associated rows of contacts. With this condition present, brush 99 performs no function; brush 40 which is connected to grounded battery at IIO will supply grounded battery through its 3rd contact to the winding of the electromagnet H. The brush 40 in posit on 3 will also connect grounded battery at IIO through a break contact of a relay III to the winding of a relay II! and'relay II! which has the otherside of its winding connected to ground at I I9 will be operated. The operation of relay H2 will connect ground at 9 through its right The relav hand make contact to the winding of relay III the other side of the winding of which is connected to the brush 40, whereupon relay H2 will .be deenergized due to the energization of relay pleted and the brush 40 engaged the 3rd contact of its associated bank of contacts 44 and at the beginning of a testing operation relay III will be locked up and relay H2 will be deenergized thereby preventing the operation of the sounder 99 until the new test is completed. The operation of electromagnet II will cause switch I9 to interconnect its middle contacts with their associated right hand contacts.

Brush 4| is also resting upon the 3rd contac of .its associated bank 45 and in that position will connect grounded battery at I I0 to the electromagnet I1 and therefore two-way switch I5 will have caused each ofits middle contacts to be interconnected with its associated left hand contact. With the electromaghets I1 and I1 energized, the clips I I, I2, I9 and I4 will connect a "quad" to the circuit to measure the capacitance between the two sides of the quad and the actual measurement of capacitance is started.

In making the first or'side to side measurement, the clips II, II, I9 and I4 will be connected to the bridge in the manner disclosed in Fig- 4; that is, the conductor associated with clip I4 will be connected to a point I49 on the bridge I30, which point I40 is connected to one side of the output winding oithe transformer IOI The clip l9 will be connected to the rotary plate I92 of the condenser I 9| and to the other side ofjthe output winding of "the transformer l0I I2 will be connected to a point I49 on the bridge I90,and to one side of the input winding of a transformer I50 which controls the recording mechanismto be described in detail hereinafter,

and the clip II will be connected to a point I5I on thebridge I80, and also to the other side of the input winding of the transformer I50. will be understood that Fig. 4 does not show all of the switches, relays, etc. which connect the wires of the cable to the bridge but is a simplified showing of the bridge with the quad connected thereto.

In making the side to side test the lower arms of the bridge I90 will have a pair of condensers I54 and I55 therein. These condensers are of equal capacitance and may be of any value which will be suflicient to balance the capacitance ofthe conductors making up the system.

The foregoing brief description of the manner in which the "quad" is connected to the capacitance bridge I90.will, it is believed, render clearer the following detailed description of the means whereby such connections are made.

With electromagnets I1 and I1 energized, clip II will be connected through switch I 5 to point I5I on'the bridge I90. through a condenser I59 to ground and through switch I9 to a point I 5| on bridge I90, clip I2 will be connected through switch I5 to po nt I49 on bridge I90. through a condenser .I50'to ground andthrough a switch I9 to a point I49 on bridge I90, clip I9 will be The clip I I82 on the bridge I30 and through a condenser I51 to ground, and clip I4 will be connected through switch I5 to one side of the output winding of transformer IOI through a condenser I58 to ground, and through switch 18- to point I48 on the bridge I30.

The condensers I51, I58, I59 and I60'are stabilizing condensers and it will be noted that condensers I51, I59 and I60 are alwaysconnected to the points I3I, I5I and I49 on the bridge, respectively, whereas condenser I58 is connected to its corner of the bridge only when a side to side measurement is being made.

With the switches 49 and 50 in the condition shown in Fig. 3, that is, with their brushes engaging the first contacts of the associated banks of contacts the first or side to side measurement is started. The side to side unbalance has been assumed to be +26 mi. and as the condenser I3l rotates through its first cycle after the start key 9| is operated, valves I45 and I41 associated with the digits 6 and 2, respectively, will be tripped.

The valves I45 and I41 will not be tripped every time their associated brushes engage a contact on the commutator, but will only be tripped when valve I56 is tripped.

The filament of valve I43 is connected through a battery I63 to an output terminal of a conventional two-stage amplifier I64, the other output terminal of which is connected to the grid of valve I43. The two-stage amplifier is conpotential of the grid of valve I56.

nected to the output side of the transformer I50, the input of which is connected to the points I49 and I5I of the bridge I 3 0. When the bridge reaches a condition of balance, the current fiowing in transformer I50 and the amplifier I64 will be reduced to a minimum. The grid of valve I43, in the absence of an alternating current input, is biased by the battery I88 sufficiently negatively so that the plate current of valve I43 is very small. When the current fiowing from the amplifier I 64 is reduced to a minimum, the reduction of current in the'plate circuit of valve I43 will make point I68, which had been strongly positive with respect-to ground, approach the The plate current of valve I43 being minimum, a minimum voltage drop across resistances I42, I81 and I80 will be in effect, therefore, the grid of valve I06 will be biased by a minimum negative voltage since the grid to filament circuit of valve I58 is closed from ground at I69 and I89 through resistances I80, I81 and I42. When the grid to filament potential difference for valve I55 has been reduced to a certain value, the plate current of valve I55 will suddenly increase, thereby causing valve I50, a gas filled valve, to trip. The plate circuit of valve I50 is closed from grounded battery at I13 through resistance I12, break contact of relay I08, resistance I10, plate and filament of valve I56, resistances I42, I81 and I 08 to ground at I89. Allvalves I45 and I41 are gas filled valves and have the same characteristics as valve I56. The plate circuit of valve I41 for tens 2 which will be similar to the plate circuits of all valves I45 and I61 will be closed from grounded battery at I13 through resistance I12, break contact of relay I08, through resistance I15, winding of relay I11, plate and. filament of valve I41, through resistances I90 and I88 to ground at I89. The grid circuit for valve I41 for tens 2 which will be similar to the grid circuits of all trip valves I45 and I41, will be closed 2,116,606 connected through a switch I5 to movable plate from the grid of valve I41 for tens 2 through resistance 230 through resistance I90 to the filament of valve I41 for tens 2. A circuit is closed from grounded battery at I13 through resistance I12, break contact of relay I08 through resistances I1I,v I90 and I88 to ground at I89 to provide a negative voltage bias throughresistance I90 to the grid of each trip valve I45 and I41. This bias on valves I45 and I41 will maintain these tubes at sufilciently negative potential with respect to their filaments to prevent their being tripped until valve I56 trips and then only when their associated brushes I44 and I46 are in engagement with segments I30 and I39 on the commutator I31. Accordingto the assumption made herein, this will occur when the brush I44 associated with digit 6 and the brush I45 associated with the digit 2 are engaging their contacts I38 and I39, respectively. When valve I56 trips, as herein above mentioned, the voltage drop .across resistance I81 is increased due to the relatively high plate current in valve I68. The efiective grid circuits for trip valves I45 and I41 for units 6 and tens 2 will be closed from the grids of valves I45 and I41 for units 6 and tens 2, respectively, through their associated commutator brushes I44 and I46, the commutator segments I38 and I39, through brush I40, through resistances I4I, I81 and I90 to the filaments of valves I45 and I41 for units 6 and tens 2, respectively. This change in potential difierence between the grids and filaments of valves I45 and I41 will cause them to be tripped. When valves I45 and I41 tripped, relay I16 for units 6 and relay I11 for tens 2 energized. With relay I18 for units 6 energized, ground is closed through the make contacts of relay I16, through one winding of relay II" for units 6, through break contacts of relay I08, through resistance I85 to grounded battery I98, energizing relay I9I for units 6. With relay I11 for tens 2 energized, ground is closed through the make contacts of relayIll, through the break contacts of relay 222, through one winding of relay I92 for tens 2 to battery I98 in a circuit as described for the I16 relay. When valves I45 and I61 are tripped, the plate current of those valves will boost the voltage drop across'resistance I96 so that the potential on the commutator I 00 of the rotating condenser I30, which connects to succeeding 'I11 and associated valves I41 in effect represent ten numbers, depending upon the path through which ground on the make contacts of therelays I11 is directed. A group of relays 222 are provided for shifting this path from ground and operate under control of the brush 59 of switch 50 which will connect grounded battery at I05 to the winding of each of the relays 222, the other side of the windings of which are connected through a resistance to ground at 223. I

The relay I9I in operating will connect ground through its winding and right hand make contact, the winding of relay I95, break contact of relay I85 and resistance I85 to grounded battery at I 93 to lock relays I95 and I9I operated until relay I86 is energized.

auaeoe The relay I52 in operating will connect ground through its winding and right hand make contact, winding. of arelay I84, break contact of relay I88 and resistance I85 to grounded battery at I88, thereby locking relays I82 and I84 operated until relay I86 is energized.

As'soon as the relays I84 and I85 are operated they operate the relay I08 in a circuit from.

.grounded battery at I98 through resistance I85 break contact of relay I86 make contacts of relays I85 and I84 winding of relay I08 to ground at I08. Upon operation of relay I08 it is locked operated over a circuit from ground at I08 through the winding of relay I08, make contact of relay I08, resistance I01 to grounded battery at I02. Operation of relay I08 disconnects battery at I18 from the valves I45, I41 and I56 and from relays I16 andl11.

After the relays I8I and I82 have been locked up as hereinbefore described and the valves I45,

I41 and I58 returned to normal, the commutator I81 in continuing its rotation will connect grounded battery at 205, through a pair of brushes 208 and 208, a conducting segment 201, winding of a relay 2I8 to ground at 2 thereby operating a relay 2I0. Upon operation relay 2I0 will connect grounded battery 2I2 through its make contact, make contact of relay I08, first contact associated with brush 58, break contact on switch 48, winding oi magnet to ground. when the switch 48 steps its brushes 58, 54, 55 and 56 to position 2 it automatically advances them step by step to position 19 by making and breaking a circuit from grounded battery at 200 through brush 58 and break contact of the switch.

As switch 48 moves its brushes from position 2 to position 19 it will cause the following operations to be performed: Brush 55 in engaging its associated contacts in positions 2, 3 and 4 will connect grounded battery to the break contacts of relays I85 and I84, respectively, but since relays I85 and I80 are operated these circuits are not effective. Brush 54 in engaging contacts 5, 6 and I will connect grounded battery at I88 through the resistance I85, break contact of relay I86, brush 62 of switch 50, in position 1, break contact of a hundreds relay 224 associated with zero, solenoid I2I associated with zero to ground to operate the solenoid and cause the registration of zero in the hundreds order of the measurement to be recorded as the side to side unbalance; brush 54 upon engaging the 8th, 9th, and 10th contacts of its bank will connect grounded battery at I88 to the left hand contacts of the relays I82 and since the relay I82 associated with the digit 2 has been operated, grounded battery will be connected through its left hand contact and the 2 solenoid Hi to ground causing the registration of 2 in the tens order of the measurement to be recorded as the side to side unbalance; and as brush 54 passes through positions 11, 12 and 13 it will connect grounded battery at I88 through the left make contact of relay I8I associated with the digit 6 and the 6 solenoid I2I to complete the recording of the side to side unbalanceby the typewriter I20 which will thus have printed on a sheet of paper the number 026 which is the unbalance assumed in the example chosen for illustration in terms of mmifs;

It is apparent that the groups of relays I8I, I82 and 220, together with the electromagnetic and vacuum tube relays and other contacts which control them, constitute a multi-denominational accumulator which upon the occurrence of a condition oi. balance in the bridge becomes fully and almost instantaneously energized to indicate the digits of the number representing the measured capacity. Although the accumulator is immediately disconnected from the rotating commutator segments which caused the registration of the correct amount, the particular denominational relays which were energized remain locked up until the digits represented by them have been successively printed through the actuation of the printing solenoids I2I.

As the brush 54 continues its movement it will engage contacts I4, I5 and I5 of its associated bank and in so doing will connect grounded battery at I88 through resistance I85 break contact of relay I86 and winding of electromagnet 41 to ground to operate the electromagnet and move brushes 88, 40 and 4i from their third to their fourth contacts.

As soon as brush 58 reaches position 19 it will connect grounded battery at I05 through brush 6I, contacts I8, 20, 2i and 22 associated with brush 58, winding of magnet 5I to ground to cause brushes 58, 54, 55 and 56 to be returned to position 1. In passing through its 20th, 21st and 22nd positions, brush 54 will connect grounded battery .at I88 through resistance I85, break contact of relay I86, brush 54, the winding of relays I86 and I86 to ground operating relays I86 and I86. Upon energization relays I86 and I86 will lock up over a circuit from grounded battery at 205 through a brush 206, a conducting segment 204, a brush 208, make contacts and windings of relays I86 and I86, in parallel to ground if the commutator I81 and condenser I8I are not in position to make a test.. The relays I86 and I86 will be deenergized as soon as the commutator and motor driven condenser are in position to make the test.

When relays I88 and I86 operated they broke the circuits which were holding relays I84, I85, I8I, I82, 224 and I08 operated. With the circuit in this condition the next time the condenser I80 moves through its range the phantom to side one test will be made since at this point brushes 88, 40 and 4i will be in engagement with their 4th contacts, brushes 58, 54, 55 and 56 will be in engagement with their 1st contacts and brushes 51,

- 58, 58, 60, III and 62 will be in engagement with their 1st contacts With brushes 40 and M engaging their fourth contacts the bridge will be set up to make a test for unbalance between the side I" and the phantom circuit by operating electromagnets :I8 and 18 from grounded battery at IIIl through the brushes 4| and 40, respectively. Brush 40 will winding of a relay 2I8 to ground to operate the relay and hold it operated while brush 40 engages its 4th and 5th contacts.

In making the phantom to side I measurement to determine the capacity unbalance between the phantom circuit and side I, the clips II and I2 as shown in Fig. 5 will be interconnected and will be connected to the movable plates I82 of condenser -.-.'I3I and one side cfthe output winding of transtests, haveequal resistances I52 and I58 therein,

55 also connect grounded battery at III! through the and that the resistances I52 and I53 may be of any value so long as they are equal.

Fig. 5 discloses diagrammatically the circuit for making the tests between the phantom circuit and side I. It will be understood that the circuit remains exactly the same in making the test between the phantom circuit and side 2, except that the connections to clips I3 and II are reversed and the connections to clips I4 and I2 are reversed.

The operation of electromagnets I6 and "will connect clips II and I2 to the movable plate I32 of condenser I3I and to one side of the input winding of transformer IOI, will connect clip I3 to a point I5I and point I5I and will connect clip I4 to a point I49 and point I49 to connect equal resistances I52 and I53 in the circuit in place of the condensers I54 and I55.

The motor driven condenser I3I will move through its range but the valve I43 'will not be tripped since the range of the condenser I3I is only mi. and the condition of unbalance has been assumed to be +102 mmf. Relay 2I3 being held operated at this time and the valve I43 failing to trip on the first revolution of the condenser I3I, the commutator I31 rotating with condenser I3I will through its conducting segment 20! connect grounded battery at 205 through. brushes 209 and 209 and winding of relay 2I9 to ground at 2I I. Relay 2"! in operating will connect grounded battery at 2I2 through make contacts of relays 2", and 2I3 and brush 53 to operate electromagnet 5I thereby to cause brushes 53, 54, 55 and 56, to be moved to their 2nd position.

As soon as brush 53 engages its 2nd contact it will complete a circuit, as described in connection with the side to side measurement, for automatically advancing brushes 53, 54, 55 and 55 through positions 2 to 19. In engaging their 2nd, 3rd and 4th contact brushes 55 and 56 will connect grounded battery at brush 290 through break contacts of relays I95 and I95 to the grounded windings of relays I86 and 95 and through brush 56 and winding of electromagnet 52 to ground. This will result in the operation of magnet 52 to cause brushes 5'! to 62, inclusive, to move into engagement with their 2nd contacts and will operate relays I96 and I96 which lock up over brushes 203 and 206 until the condenser MI is in position to make tests.

The brushes 51, 59, 59, 60, 5! and 52 in position 2 perform the following functions: brush 51 prepares a circuit from strapped contacts H to I 9 associated with brush 54 through brush 51 and winding of electromagnet 52 to ground, brush 58 will complete a circuitfrom grounded battery at' I05 to operate a relay 220, brush 59 completes a circuit from grounded battery at I 95 to operate all relays 222, brush 50 completes a'circuiti'rom grounded battery at I05 to operate electromagnet I9, brush 6i completes a circuit from grounded battery at I05 to operate electromagnet 92, and

I brush 62 will prepare'a circuit from contacts 5.

6, and I, associated with brush 54 to the break contact of relay 224 for zero, make contacts of zero relays I9I and I92, a make contact 01' 10 relay I92 and zero solenoid I2l.

with the circuit in the condition just described, a- 50 mt. condenser 2" will be connected across the bridge from point I32 through condenser 2 I9. make contact of relay 225 switches I9, 92 and I9 to point I49 oi. the bridge.

As the motor driven condenser III passesthrough its range an eil'ective measurement or the phantom to side one circuit will be made for an unbalance ranging between 52 mi. and 110 mini. and no balance. being reached, (the unbalance having been assumed to be +102 mmf.) the valve I56 will fail to trip. Therefore, relays I86 and I96 will be operated over a circuit from grounded battery at brush 55, and break contacts of relays I94 and I95 and held energized through brushes 203 and 206 and brush 54 in passing over its associated contacts 5 to 22 will 10 be ineffective. The operation of relay I96 will connect grounded battery through make contact of relay I96 to contacts I9 to 22, inclusive, asso-.

ciated with brush 53, to cause electromagnet 5| to operate four times and return brushes 53 to 56 to position 1. It will then be necessary to measure the unbalance of the phantom to side one circuit in the range +52 mmf. to +110 mmf. and when relay 2 I 0 operated as the condenser I3! moved out of its effective range on the previous measurement it connected grounded battery to contact I associated with brush 53 and started the brushes 53. to 56, inclusive, moving through positions 2 to 19.

The circuit is arranged to make the test in the range +52 mini. to +110 mmf. by brush 55 connecting grounded battery through its 2nd, 3rd and 4th contacts, break contacts of relays I95 and I94 brush 56 engaging its 2nd, 3rd and 4th contacts to energize electromagnet 52 and cause it to step brushes 5! to 62 into engagement with their third contacts. Brush 5'! is ineiiective since its third contact is connected to contacts II, I8 and I9 associated with'brush 54. Brushes 58. 59, 5| and 62 will maintain the same circuits in position -3 as they maintained in position 2. Brush 60 in engaging its 3rd contact will connect grounded battery at I05 through electromagnet to ground, thereby causing condenser 2| 8, to be transferred from its previous positions in the circuit to the following positions: One side of condenser 2I8 will be connected to the movable plate of condenser I3I and the other side will be connected to point I5I.

When the condenser I3I moves through its range again a measurement of the phantom to side I circuit will be made in the range +52 mini. to +110 mmf. and as the bridge reaches a condition of balance valve I56 will .trip at the time when brush I44 associated with the digit 2 is engaging its associated contact I38 and brush I46 associated with the digit 5 in engaging its associated contact. Relays 222 being energized at this time, the operation of valve I4I associated with the digit 5 will cause the operation of relay I92 associated with the number 10.

The unbalance of the phantom to side one circuit will now be recorded. The relay I92 associated with the number 10 being operated will operate relays 224 in a circuit from grounded battery at I93, break contact of relay I86 make contact of relay I92 associated with number 10, and windings of relays 224 to ground. When relays I9l and I92 associated with the numbers 2 and 10 operate they will lock operated over a circuit through their right hand make contacts, windings of relays I and I94, respectively, to grounded battery at I93.

As the condenser I3I moves out of its eflective range after the relays I9I, I92 and 224 have been locked up it will through brushes 209 and 209 again cause the energization of relay 2! and start brushes 53 to 56 moving through their cycle to record the unbalance. .Brush 54 will in engaging its 5th to 13th contacts connect grounded battery at I93 through brush e2 successively through make contact of relay 224 associated with zero which operated when relay I92 for digit 10 operated, to the winding of the solenoid l2l for printing the digit 1, make contact of relay I92 51 to 6 2 return to the position where they engage their first contacts. Brushes 53 to 56 in return ing to position 1 will pause momentarily at position 19 since relay I96 will be deenergized and while brushes 53 to 56 are standing in position 19 brushes 5'! to 62 will be advanced to position 1 due to the completion of a circuit from grounded battery at W3 through break contact of relay I86 brush 54 strapped contacts 2 to 22 and brush 5] to the winding of velectromagnet 52. As soon as brush 6! reaches its 1st position it will complete the circuit for returning brushes 53 to 56 to position 1. Brush 5% in passing through positions 20, 21, and 22 will operate relays I86 and I96 and prepare the circuit for the next test. Brushes 39 to 4| will have been stepped into engagement with their 5th contacts by brush 54 passing through positions 14, '15 and 16 with relay I86 deenergized.

Brush M in engaging the 5th contact will main-. tain the circuit in the same condition as it was in making the phantom to side one test. But brush M in engaging its 5th contact will connect grounded battery at Hi! to electromagnet H to operate the electromagnet and interchange the connections running to clips H, l2, I3 and M. With the electromagnet ll energized clip It will be connected to point 9; clip l3 will be connected to the movable plate of condenser I31! and clip It will be connected to point 8'. As will be obvious, this is simply a reversal of the connections of the clips andthe test to be made will be the exact opposite of that made in connection with the phantom to side i test.

It has been assumed that the phantom to side 2 unbalance is -256 mmf. Therefore, a condition of balance will not be reached until selector switch 52 has moved its brushes to the 9th contacts in their associated banks. In moving into association with the 9th contacts of their associated banks the brushes 51 to 62 will arrange the circuit to make the tests previously described in connection with the phantom to side I test and in addition the selector switch 52 will successively add lumpsof capacitance to the bridgeby successively through brush 58 operating relay 221i and three similar relays 225, 226 and 221 to connect condensers 2, 230, 2%" and 232 associated with said relays to the circuit if necessary. The

condensers 2m, 230, 23l and 232 associated with relays 221i, 225, 22c and 221 have a capacitance valueof 50 mmf., 100 mm f 150 mini. and 200 mmf., respectively.

I printing ,cycle takes place, be connected to the relay 22% associated with the digit 2 and as a result the condenser l3l, upon reaching the position where it of itself has added 56 rnmf. to the minus side of the bridge circuit, 200 mmf. having been added to the bridge due to the operation of relay 221, will balance the circuit and the numbers 2, 5 and 6 will be recorded as indicating the phantom to side 2 unbalance of the cable quad. After recording the phantom to side 2 unbalance brushes 53 and 62 will be returned to position i in the same manner as described in connection with the phantom to side i unbalance, and brushes 39 to M of selector switch 38 will be stepped into position 6 preparing the bridge for a new test.

In position 6 brush 40 will complete a circuit for operating relay H2 from grounded battery H0 through brush 40 and the winding of the relay H2 to ground at H3. As soon as relay H2 operates, it will complete a circuit for operating relay III as follows: Grounded battery at H0 through brush 40, winding of relay I II and make contact of relay H2, to ground at H3. The operation of relay H2 will connect, grounded battery at H5 through sounder 98, operating the sounder and shunting the current through make contact of relay 95 to disconnect the 900 cycle alternating test current from the bridge circuit thereby notifying the operator that the test has out departing from the scope of the invention which is to be limited only by the appended claims. a

What is claimed is:

1. In a capacitance measuring machine, abridge circuit, means for connecting-an article to said bridge circuit, and means interposed between the bridge circuit and the connecting means and operable in a predetermined cyclic manner in re-.

sponse to a measurement made by the bridge circuit for changing the connections between the article and the bridge to make a series of capacitance tests.

2. In a capacitance measuring machine, a bridge circuit, means for connecting an article to said bridge circuit, means interposed between the connecting means and the bridge circuit and operable in a predetermined cyclic manner in response to measurements made by the bridge circuit for changing the connections between the' article and the bridge to make a series of capacitance tests, and means controlled by the bridge circuit and said cyclically operated means for recording the numerical values of the capacity measured.

3. In a measuring apparatus formeasuring capacity unbalance in a telephone cable, an electrical circuit, means for securing the cable to the circuit, means interposed between said circuit and the means for connecting the cable to the circuit for changing the connections to make a series of tests in automatic succession, means controlled by the circuit for translating the measurements made into numerical values, and means controlled by said translating means for recording the numerical values of the measurements made.

4. In a measuring and recording apparatus, a bridge circuit, means for connecting an article to be measured to the bridge circuit, means for applying a test current across the bridge, a bridge output circuit including a thermionic valve which is tripped when the bridge circuit reaches a condition of balance, a series of thermionic valves and a commutator mechanism connected to said bridge for registering the amount of capacitance is reached, and means controlled by said series of valves for recording the numerical value 01' the amount of capacity added to the bridge to balance it.

5. In a measuring and recording device, a capacity unbalance bridge, an input circuit for applying a test current to said bridge, an output circuit operable when a condition of balance is reached in the bridge circuit including'a thermionic valve which trips when the bridge circuit reaches a condition of balance, circuits controlled by said thermionic valve for indicating the amount of capacity added to the bridge to ballast mentioned circuits for recording the numerical value of the unbalance measured by the bridge.

6. A measuring device comprising means for making a measurement of an electrical characteristic of an article, and means controlled thereby for making a record of said measurement including thermionic valves representing digits operated under control of the measuring device for controlling the recording of the characteristic measured in numerical terms, said valvesbeing less in number than the digits which they represent.

'7. A measuring device comprising a circuit for measuring characteristics of an article, means for recording a measurement in denominational columns including thermionic valves representing the units denomination to berecorded,andthermionic valves representing the tens denomination to be recorded, said tens denomination representing valves being less in number than the number of denominations which they represent.

8. An apparatus for measuring capacity unbalance in telephone cables comprising a self balancing bridge circuit, means for connecting the wires a telephone cable to the bridge in a plurality of difl'erent ways, means for applying test current to the bridge, and means controlled by the bridge for recording the measurements made thereby.

9. An'apparatus for measuring an electrical characteristic of an article comprising an unbalance capacitance bridge circuit, a motor driven air condenser in said circuit, a commutator driven in synchronism with said condenser, a bridge balance detector controlled by said bridge circuit for rendering said commutator effective, and a recording means controlled by the commutator and balance detector for recording numerically the unbalance between'predetermined parts of the article.

10. In a measuring device, an electric impedance network, means for cyclically varyingsaid network, a commutator synchronously operable with said varying means, a plurality 01' indicating devices controlled by said commutator, and means controlled by a condition in said network for actuating an indicating device selected by said commutator.

11. In a testing device for multi-conductor cables, a circuit for making a plurality of tests on said cable, circuits rendered eflective under control of said testing circuit, and electrically operated switches controlled by the last mentioned circuits for automatically and sequentially connecting conductors 01' said cable, to said circuit in a plurality of diflerent ways.

added to the bridge before a condition of balance 12. In a measuring and recording apparatus, a set of relays less than ten representing the digits of a denomination, certain of said relays representing more than one digit, a recorder, and means for shifting the output circuits of said double function relays from one portion of the recorder to another part.

13. In a measuring device, a bridge network having input and output circuits, a thermionic valve having a grid and a cathode connected to the output circuit whereby a reversal of phase of the current in the output circuit will render the thermionic valve efiective, and an automatic selector switch controlled by said thermionic valve for adding an impedance element in said bridge circuit.

14. A measuring device for measuring electrical characteristics of multi-conductor cables, means for automatically and sequentially connecting conductors of said cable in a plurality of diiferent ways for making measurements of the characteristics of said cable, bridge circuits associated with said connecting means and responsive to an electrical characteristic of said cable, means controlled by the bridge circuits for selecting and printing the digits composing the numbers representative of the values of measurements made by said bridge circuits, and means for recording said digits in their proper order to indicate said numbers.

15. In a capacitance measuring apparatus, a bridge circuit, means for connecting an article to said bridge circuit, a power source controlled by the bridge circuit and switches interposed between the connecting means and the bridge circuit and driven by power from said source in a predetermined cyclic manner for changing the connections between the article and the bridge to make a series of capacitance measurements.

16. In a capacitance measuring apparatus, a bridge circuit, means for connecting an article to said bridge circuit, a power source controlled by the bridge circuit, and switches driven by power from said source in a predetermined cyclic manner for changing the connections between the article and the bridge to make a series of capaci-' bridge circuit, a source of current applied to said bridge circuit, an output circuit for said bridge circuit, an indicating device controlled by said output circuit when the bridge reaches a condition of balance, means for changing the range of the bridge progressively including-a series of selector switches operable under control of the output circuit of the bridge, and means connected to the output circuit 01' the bridge for causing the value of the characteristic being measured to be registered when the brid e reaches a condition of,

- balance.

CLAIR L. LEMMON. l 

